Check if the files are in the "C:\Users\"your name"\Saved Games\DCS.openbeta\Kneeboard\P-51D" folder.
Check if the files are in the "C:\Users\"your name"\Saved Games\DCS.openbeta\Kneeboard\P-51D-30-NA" folder.

A pair of printable PDF checklists is inside this folder as well.

Remember to adapt the path to your username and DCS version you are using.

You will find the checklist on your DCS Kneeboard. If you have more than one DCS version, repeat the step above to each version.

Good luck and fly safe!
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Bem-vindo a Série de Checklists Rápidos.